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We describe here a new type of analog correlators based on stationary waves recovery and spatial Fourier transformation. The theoretical basis of the stationary waves integrated Fourier transform spectrometer (SWIFTS) is first introduced. Based on robust physical principles validated by circuits type simulations, the spectrometer could be an interesting competitor to actual RF analog correlators. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1138–1142, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22375

Within the framework of a program aiming to improve the existing extractive recovery technology of fermentation products, the state of the art is critically reviewed. The acids under consideration are propionic, lactic, pyruvic, succinic, fumaric, maleic, malic, itaconic, tartaric, citric, and isocitric, all obtained by the aerobic fermentation of glucose via the glycolytic pathway and glyoxylate bypass. With no exception, it is the undissociated monomeric acid that is extracted into carbon-bonded and phosphorus-bonded oxygen donor extractants. In the organic phase, the acids are usually dimerized. The extractive transfer process obeys the Nernst law, and the measured partition coefficients range from about 0.003 for aliphatic hydrocarbons to about 2 to 3 for aliphatic alcohols and ketones to about 10 or more for organophosphates. Equally high distribution ratios are measured when long-chain tertiary amines are employed as extractants, forming bulky salts preferentially soluble in the organic phase.

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Coextraction of water during extraction of succinic acid by Alamine 336 in different diluents has been measured. The amounts of coextracted water lie in the same order as the solubilities of water in the diluents without amine present. Water coextraction with different acids follows the order fumaric > malonic > maleic = succinic > lactic > acetic. The effects of temperature on extraction of succinic and lactic acids by Alamine 336 with chloroform and methyl isobutyl ketone (MIBK) diluents have been measured. Enthalpies and entropies of complex formation have been derived from the results and are interpreted in terms of the differences in interactions among the species involved. Two approaches for regeneration through back-extraction into an aqueous phase are considered. These involve changes in the equilibrium relationship through a swing of temperature and a swing of diluent composition, respectively. The factors underlying the utility of each are explored and contrasted. The two approaches may be used in combination.In the production of carboxylic acids, processes such as fermentations produce multicomponent, aqueous solutions with product acid concentrations typically 10% w/w at most, and usually substantially less. Subsequent separation, purification, and concentration of these acids is difficult because of the high affinities of the acids for water.Distillation of dilute, nonvolatile acids involves large energy consumption for the heat of vaporization of water, which must be taken overhead. Furthermore, distillation cannot fractionate among nonvolatile acids. The low aqueous Biotechnol. 1983, 33B, 85-94.

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